Ophiomastix wendtii

Lore & Background

Ophiomastix wendtii was originally named Ophiocoma wendtii by J. Muller and F. H. Troschel in 1842. In 2018, Timothy O'Hara reclassified it under the genus Ophiomastix, one of four genera previously thought to constitute Ophiocoma. The genus Ophiomastix is characterized by bearing spines twice as high as they are wide. A proposed name, Ophiocoma riisei, was suggested by Christian Frederik Lütken in 1856 but never commonly accepted. The etymology of wendtii supposedly comes from a Captain Johann Wilhelm Wendt.

The species inhabits reef rubble of the Caribbean Sea, particularly in the Gulf of Mexico, and is most commonly found near Belize and Costa Rica. It has been reported as far south as near Brazil and also in the Mozambique Channel between eastern Africa and Madagascar. It is typically found within a depth range of 1 to 27 meters. O. wendtii is considered among the macrobenthos functional group, alongside its fellow Ophiuroidea.

O. wendtii bears long, club-shaped spines on its arms and can change color by means of phototropic chromatophores. It is typically deep crimson, fading to neutral beige at night, and its color can be artificially changed by alterations in light exposure. Its arms are covered with calcite crystals, thought to be reinforced with magnesium-rich nanoprecipitates to make them more difficult to crack. Like other echinoderms, it forms a mineralized skeleton. It is averse to light, preferring to come out at night, and its pluteus larvae are planktotrophic.

Reader's Guide

Ophiomastix wendtii holds significance in the study of echinoderm vision and biomaterials. The calcite crystals on its arms were, until recently, thought to form a visual system that minimizes spherical aberration and focuses light on an underlying photoreceptor system, with nerve bundles under each lens transmitting optical information. However, the discovery of nerves and photoreceptor cells in between, rather than beneath, the lenses suggests this system may not rely on the crystals' optical properties. The only known animals to employ a similar visual system were the now-extinct trilobites. Researchers found that O. wendtii could actively search out areas based on color contrast, suspected to be a behavior designed to evade predators. Its color-changing ability may also play a role in its complex vision system. The species' protective arm crystals, reinforced with magnesium-rich nanoprecipitates, offer insights into biomineralization and fracture resistance. As a member of the macrobenthos functional group, it contributes to reef rubble ecosystems. Its reclassification in 2018 by Timothy O'Hara highlights ongoing taxonomic revisions within the Ophiuroidea, and its wide distribution from the Caribbean to the Mozambique Channel raises questions about dispersal and biogeography.

Did You Know?

• Ophiomastix wendtii was originally named Ophiocoma wendtii in 1842 by J. Muller and F. H. Troschel.
• Its calcite arm crystals were once thought to form a visual system similar to that of extinct trilobites.
• The species can change color from deep crimson to neutral beige using phototropic chromatophores.
• It has been reported in both the Caribbean Sea and the Mozambique Channel.